Group III-V compound semiconductors, such as GaN and AlGaN, have been widely used in the field of optoelectronics and electronic devices since such semiconductors have wide and easily adjustable band gap energy and other advantages.
In particular, a light emitting device, such as a light emitting diode or a laser diode, using a group III-V or II-VI compound semiconductor material may emit various colors owing to the development of thin film growth technology and device materials. For example, the light emitting device may emit high-efficiency white light by using a fluorescent material in conjunction with red light, green light, blue light, and ultraviolet light, or by combining colors. The light emitting device exhibits low power consumption, a semi-permanent lifespan, a short response time, good safety, and environment-friendly characteristics, compared to conventional light sources, such as fluorescent lamps and incandescent lamps.
Consequently, the light emitting device has been variously used in a transmission module of an optical communication system, a light emitting diode backlight unit that substitutes for a cold cathode fluorescence lamp (CCFL) constituting a backlight unit of a liquid crystal display (LCD) display apparatus, a white light emitting diode lighting apparatus that substitutes for fluorescent lamps and incandescent lamps, vehicle headlights, and signal lamps.
A light emitting device (not shown) includes a light emitting structure (not shown), which includes a first conductive semiconductor layer (not shown), an active layer (not shown), and a second conductive semiconductor layer (not shown). A first electrode (not shown) and a second electrode (not shown) are disposed on the first conductive semiconductor layer (not shown) and the second conductive semiconductor layer (not shown), respectively. The light emitting device (not shown) emits light having energy set by the inherent energy band of a material constituting the active layer (not shown) as the result of coupling between electrons injected through the first conductive semiconductor layer (not shown) and holes injected through the second conductive semiconductor layer (not shown). The light emitted from the active layer (not shown) may be changed depending on the composition of the material constituting the active layer. For example, blue light, ultraviolet (UV) light, or deep UV light may be emitted from the active layer (not shown).
In the case in which the light emitting device is used in a lighting apparatus or an LCD backlight unit, a light emitting device package may further include a lens disposed on one surface of the light emitting device in order to widen the viewing angle of the light emitted by the light emitting device.
In general, the lens provided to widen the viewing angle of the light emitted by the light emitting device may be classified as an integrated lens or a separate lens depending on the position of the lens.
FIG. 1 is a view showing a conventional light emitting device package.
The conventional light emitting device package may include a light emitting device 100 for emitting light, the light emitting device 100 including a first conductive semiconductor layer (not shown), an active layer (not shown), and a second conductive semiconductor layer (not shown), a lead frame 222 disposed on one surface of the light emitting device 100 for supporting the light emitting device 100, and a lens 300 disposed outside the light emitting device 100 for refracting the light emitted by the light emitting device 100.
The light emitted by the light emitting device 100 is refracted by the lens 300 and is then output to the outside.
In the conventional light emitting device having the integrated lens described above, however, only a single refraction surface that is capable of adjusting the advancing path of the light emitted by the light emitting device 100 is provided. As a result, freedom in the design of the light emitting device package is reduced, and is limited to widening the viewing angle of the light that is emitted by the light emitting device.